helicoil
When the belt tensioner fails, you have to stop almost immediately or the engine will overheat and suffer serious damage or destruction. I am assuming that the bolt itself is not stripped; the receiving mounting hole in the engine is stripped. And I am pretty sure that the mounting area is aluminum. Therefore, it should be fairly easy to tap the hole for an over-sized bolt. Select a tap that is just larger than the stripped bolt. I would not recommend the JB weld since if it fails, you are stuck without warning. Best of luck!
Ask the garage for a helicoil repair.
If you mean the head of the bolt is stripped, there is a tool called a back out. You employ it by drilling the right size hole in the top of the bolt, inserting the backout. The backout, when turned, will grip the bolt inside the hole sufficiently to turn it. Also drilling a hole through the bold will take the pressue off the threads of the bolt and with a paid of vice grips you may be able to turn it. I'd try the backout, it's nearly fool proof.
If a bolt is stripped on the windshield wiper on a 1995 Subaru Legacy Wagon, there are two options. A person can go to a salvage yard and purchase new wipers for the vehicle, or they can have the bolt hole tapped for a larger bolt.
Use an easy-out of harder metal after drilling a small hole with harder metal.
Repair kit availale at most auto parts stores
Here are 3 options for you at this point: 1. Bring the head into an automotive machine shop for them to repair it; 2. Repair the stripped hole in the head with an insert 3. Buy a new head, rebuild the engine from the head gasket up.
I'm not sure exactly what your working on but it sounds like a "heli-coil" would do the trick. Stop in your local auto parts store and ask them for a "heli-coil" kit to repair the size bolt you have. The kit will supply what is necessary to repair the threaded hole back to original.
Get a device called and easy out. You have to drill a hole in the bolt first (assuming it is thick enough to be drilled). Once drilled you screw in the easy out in a reverse direction and the bolt gets undone in the process. Use a good penetrating lubricant overnight before attempting.
to replace a stripped head bolt, you will need to remove the head. very carefully you willneed to drill out the bolt hole in the head. you can then retap a thread into the new hole and use a larger headbolt, or you can use a speedythread to replace the thread to the original size.if you are not mecahanical i would have a mechanic do this. do not let them tell you that it cannot be fixed,or you will be replacing the motor or the engine block.
If the sensor is stripped you will have to replace it. If the fitting or hole it threads into is stripped it is likely you can make oversize threads and use a fitting called a bushing to repair it. Mind you I got desperate one night and epoxied one in. Its still working but if I ever have to change it I am toast.